Hydatid cysts are most common in the liver followed by lungs. Most are asymptomatic for prolonged periods. The other sites where hydatid cysts are found include the spleen, kidneys and brain. Retroperitoneal hydatid cysts are extremely rare. A 45-year-old male presented to the authors’ emergency room with history of abdominal pain over the previous 7 days. It was insidious at onset and the pain had increased in severity during the 2 days before arriving at the hospital. The pain was radiating to the right lower limb. The abdomen showed a tender vague mass in the right lumbar region and iliac fossa. A CT scan confirmed a hydatid cyst in the retro peritoneum. The patient underwent laparotomy and excision of the cyst. [Arch Clin Exp Surg 2017; 6(3.000): 162-164]